Visual lateralisation effect in reading Chinese characters

Abstract

Visual half-field experiments have been used to investigate perceptual differences in reading different types of writing scripts. It has been observed that tachistoscopic recognition of phonetic-based scripts (such as the English alphabet and Japanese Kana) tends to show a right visual field–left hemisphere (RVF-LH) superiority effect^1,2 whereas recognition of logographic symbols (for example, Chinese characters) tends to show a left visual field–right hemisphere (LVF-RH) superiority effect^3,4. A cerebral orthography-specific localisation hypothesis has been proposed to account for these data. We have conducted three experiments to examine the visual lateralisation effect in reading logographic symbols such as Chinese characters. Chinese subjects in the first experiment were exposed to brief tachistoscopic presentation of a single character, and their task was to name the character as soon as possible. A LVF-RH superiority was found. In the second experiment, the stimuli were two vertically arranged characters and the subjects were asked to name the stimulus terms as soon as possible. The third experiment was the same as the second except that the task was to decide whether these character-strings were correct semantic terms with a manual response. A RVF-LH superiority effect was found in both the second and third experiments. These differential visual lateralisation results were interpreted as reflecting the function-specific property of the two hemispheres and cast doubt on the orthography-specific localisation hypothesis proposed by earlier investigators.